XPath Date Formatting Problem

Hey all, just plain and simple I think....lol
Why will this not work?
<asp:Label ID='playDate' runat='server' Text='<%# XPath("LastPlayed", "{0:MMM d yyyy}") %>'></asp:Label>
It completely ignors my date formating and returns this result.
2010-09-18T13:37:37+00:00
Oh yea, this is in a datalist using an XML datasource.

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